Higher Phosphorus Levels Linked to Mortality

The findings generally support KDOQI guidelines for dialysis patients, which recommend maintaining serum phosphorus levels between 3.5 and 5.5 mg/dL.

Patients with higher baseline levels of phosphorus, ranging from 3.5 to more than 7.5 mg/dL, had a greater risk of mortality.

Hemodialysis (HD) patients with a high serum phosphorus level that subsequently rises have a greater risk of early death compared with those with a stable level between 3.5 and 5.5 mg/dL, according to new research presented at the National Kidney Foundation 2015 Spring Clinical Meetings in Dallas.

For the study, investigators led by Kamyar Kalantar-Zadeh, MD, MPH, PhD, of the University of California, Irvine Medical Center and medical director for nephrology at Renal & Urology News, examined the change in serum phosphorus levels in nearly 96,500 patients receiving maintenance HD from 2007 to 2011. A rise or decline of serum phosphorus by more than 0.5 mg/dL after baseline was noted. More than half of patients (60%) had diabetes, 43% were female, and 32% were African American. The average age was 63.

After adjusting for potential confounders, patients with higher baseline levels of phosphorus, ranging from 3.5 to more than 7.5 mg/dL, had a greater risk of mortality. This was especially true for those who had a rise in their phosphorus levels 91 days later.

Greater mortality was also seen among patients with low baseline phosphorus (below 3.5 mg/dL), whose levels declined by the next quarter.

Whether decreasing phosphorus levels to the Kidney Disease Outcomes Quality Initiative (KDOQI) recommended target (3.5 to less than 5.5 mg/dL) might improve mortality should be investigated, according to the researchers.